Bicycle tracks

Here is a passage from a Sherlock Holmes story, The Adventure of the Priory School (by Arthur Conan Doyle):

`This track, as you perceive, was made by a rider who was going from the direction of the school.'

`Or towards it?'

`No, no, my dear Watson. The more deeply sunk impression is, of course, the hind wheel, upon which the weight rests. You perceive several places where it has passed across and obliterated the more shallow mark of the front one. It was undoubtedly heading away from the school.'

1. Discuss the passage above.
2. Visualize, discuss, and sketch what bicycle tracks look like.
3. When we present actual bicycle tracks, determine the direction of motion.
4. What else can you tell about the bike from the tracks?